Sigh...first major bill for owning used truck

usage and temp didn't cause your problem. those miles are low for an avg transmission and those temps aren't bad. I'm sure you have a water/oil transmission cooler. you engine runs through a cooler your trans fluid also runs through so it will run warm.

and it's doubtful your transmission is actually shot, sounds like a problem with the shift rails of something as someone else stated

 

Any good machine shop should be able to turn it.

 

When you say it wont go int 3/4/7/8 what happens? The stick wont move into those positions or it does but seems to still be in neutral or it grinds and refuses to go into gear?

I would pull the transmission and remove the top cover/shiftbar assembly and see what went wrong. It could be a very simple fix. Any mechanic worth his paycheck should be able fix it and look inside the transmission and tell you if it has some life left.

If the transmission is out yes replace the clutch! The flywheel will need to be resurfaced. Any shop that replaces clutches will have an arrangement with a machine shop or own the necessary equipment. Since the flywheel is off its not a lot of work to replace the seal. Replace it!

Oil leaking into the flywheel housing. The front seal on the transmission is not a lip type seal, its a spiral groove cut in the input shaft that pushes any oil that tries to get past it back into the transmission. If it leaks the transmission is overfull, the vent is plugged or you have an air cylinder leak inside the transmission. An air leak inside the transmission will usually cause shifting problems as well, so I doubt that is your problem. Transmission oil can leak through some of the bolts that hold the bell-housing to the transmission.
The shop repairing the transmission will probably install an input shaft kit in the transmission as the shaft wears where the clutch splines drive it. The kit comes with gaskets for the bell-housing although you can replace the input shaft without removing the bell-housing make sure they know there is a leak and they address it. Make sure the throw-out fork gets replaced as well.

Your truck should have an air assisted hydraulic clutch. The fluid in the reservoir seems to disappear over time I suspect leakage past the cup seals. When the fluid gets low the first complaint is that the clutch brake doesn't work.Sometimes you can get away with topping up the reservoir sometimes the clutch hydraulic circuit has to be bled.

 

Can you shift the trans into the 3-4 gear position or 7-8 gear position when the engine is not running.

Does it bind or grind when running? Pull an oil sample in to a clean container and inspect it with a flashlight to check for metal particles and shavings.

It sounds like you may have a possible twisted main shaft, a shift collar problem, a speed gear problem with the internal gears that accept the shifting collars, or even a bent shift fork, or problem within the shift bar housing as well. It could be a number of things or a simple fix.

 

Brand new non reman was $7800 I was told a few weeks ago for another truck that I was looking at to take the pos fro 10 out

 

Well I had my cars flywheel and head rebuilt at a machine shop, sometimes I don't think before speaking but I was just wondering if they'd even take that on being much bigger, then I thought about how that same shop had all kinds of buses, tractor, semi and other rigs sitting out there.

 

Any time your shifter moves. It's a broken mount. And I believe there's usually 3 mounts.

Have had it happen a couple times.

 

Clutches are generally a "while you're in there" when you do a transmission job, regardless of vehicle type, because you have to drop the transmission to get at the clutches anyway. So yes, I definitely recommend doing your clutch replacement at the same time. It'll save you on several hours of labor down the road

 

The operative words here are:

owning a used truck

Whatever abuse this truck was exposed to is going to show up now and in the future. A premature broken engine/trans mount could indicate the previous driver(s) were not very smooth with the operation of the truck.

It stands to reason if the mount gave it up because of poor driving habits, the clutch (if it hasn't already been replaced once) and other driveline components, transmission, driveline, power divider etc. are at risk. Watch for symptoms there as you drive it. Noises, leaks etc.
You "saved" money by buying a used truck. Now you get to spend money repairing anything that may fail because of the previous incompetency( either driver or maintenance)

I would be very proactive on this. Do the mount(s), clutch, rear main seal(optional, i had trouble with improperly installed rear main seals causing a leak instead of solving them). The transmission is a big ticket item. cheaper to do it now than a tow on the road which negates any scrimping on the investment.

The trucking industry has gone to automated manuals in an attempt to prevent all of these types of problems. i don't think it solved any of them.